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W. Tripp

Hull Balance

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NO

For a given boat at a given speed there will be point X inches from the rear of the transom that will yeild best results if the boat were to be set up on a saw horse and balanced there. On the STV River Rocket and Euro this point is right in front of the fuel tank - as a rule of thumb. The ModVp's are different.

If you have X amount of engine set back, and go to X+2 inches, then the balance point of the boat has moved backwards, and now the boat will need to be rebalanced to get the original balance point.

The ONLY way to find where your hull wants to be balanced for best handling and speed is by testing. What I like best may not be what you or the next guy like best for how they use their boat.

If you are set up for drags using a 22p Yamaha, and then want to run top end with a 32p Cleaver - expect the boat to want different set up, or bend the prop to match the set up of the boat.

You wouldn't believe how much I play with weight for each prop I race on my DR-20.

.05 seconds can mean a win or a loss. And moving 10 pounds 6 inches can make a diference.

-Wayne

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Thanks guys for your info. I'm setting my boat up next week if the new motor ever gets deliverd from Merc. Heres what I have.

2004 3 seat stv river rocket 750lbs Never beeen set up

28 gallon tank

Set up for a 15" mid

2005 280 15" offshore race/sportmaster as from the factory. Rev limiter to be raised to 9000 to 9200 for now.

5 inch hydro dynamics jack plate as from Wally

optima battery(appro 50lbs)

The battery box was as Wally placed it.

I weigh around 230 with gear on.

Do you guys have any starting recommendations on where to locate. trim pump, fuel pump,water seperater, move the battery?

The boat is mainly driven for fun on the weekends. Some top end numbers. Weekly racing on a short 700 to 800 ft track. 22 pitch prop.

Hears a few pics. Thanks in advance Kurt

post-635-1110928178.jpg

post-635-1110928198.jpg

post-635-1110928218.jpg

post-635-1110928261.jpg

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Kurt,

My .02:

For the standard weight River Rocket hulls, The battery location is just fine for most use. If you want to get as crazy as a few of us are about balance, mount everything as far forward as possible under the back deck - on either side of the tank. But this is not really needed for a 280 powered boat. Mounting to the knee braces is quick, easy, and works well - especially when you are carrying passengers and gear.

I am not a big fan of the Optima batteries in boats, but it will work fine. The Odessey batteries are lighter and last longer. They also release energy and charge better than the Optimas that can have plate cracking issues with the spiral wound design of the cells. But the Optima is fine.

Mount the trim pump opposite the battery on the other side of the tank as far forward as will fit on the knee brace. I really like using the Mercruiser trim pump for either 12v or 24v trim. It is considerably quicker and better built for high performance applications, but the standard pump will work well.

If you later want to change to quicker trim for occasional racing the Mercruiser pump and the short Offshore trim ram will work well on 12v and 24v if you feel you need more.

I like to mount the fuel pump behind the tank at a low level, and place the fuel filter where it ccan be replaced easily. If you monitor your fuel closely (for water) as it enters the tank, you do not need to use the water seperator.

Cut a hole in the top of the fuel tank and mount a fuel cell filler cap assembly. This will be MUCH easier to use than the filler mounter on the back of the boat. But the manufacturer cannot do this due to USCG regulations. Trust me, it is worth the time.

If your boat has seatiiiiing for two up front, get a bag of lead shot from a hunting supply store and wrap it in plastic and duct tape. Use this in the left hand side pocket to offset your weight for solo runs.

I hope this helps.

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What Wayne said is about where I would do it too. ( Wayne he has done the tank mod though ).

Rob, yes the fuel tank is over the bulhead. There is a carbonfiber bracket that holds the tank off the floor to clear it. Infront of the tanks are 3 batterys.

RT

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Thanks Wayne for the advice. The set up you talk is what I had on my first river rocket. It worked out real good. I'll do that again on this boat . I found out that on my other river rocket, I didnt need that fast of a trim set up. There was very little trim variation needed. I think faster trim set up would have been to fast on that boat.

My Euro was a different boat though. I could not get it balanced out no matter what I tried and I tried most everything that you talked about. The only time I could drive it real fast as a perfect set up was in perfect glass like water conditions. It was awesome than. When the water was a little choppy, it was a whole different story. I never did figure out the best set up on that boat. Thanks for the help. Kurt

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Kurt,

I got to meet the guy you bought your Euro from (I hope he is the real one, he said he was) last Thursday and I have an interesting story to tell you. It might explain the problems with the set up/balance of your Euro AND it might shed some light on your sideways trip that unfortunately happened. There is more to the equation than I ever imagined. I will save this for between us so call me sometime.We need to talk about the summer events anyway. We are trying to hook some of the Blarney events and Kosh with the ones I wrote you about.

Randy

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Oh............. This is getting real interesting. Are his intials D. L. ? Randy,I'll try getting a hold of you later this morning. I sure wish I had time right now. Kurt

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Does any one have Randys # I cany seem to find it in me fine filing system I have here. Thanks Kurt

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How do you guys go about determining the left/right balance exactly? Mine has always seemed heavy on the drivers (stb) side. Seems to run better with a passenger, but not always.

I have already moved the battery to centered in front of the tank, from the stb side of the tank. The trim pump is on the port side of the knee next to the tank. I usually carry my spare prop on the port side, but I have room for 2 spares.

How do you guys weigh the thing?

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The lead shot bag works for all boats. Lead shot will not hurt anything if it bounces around a bit - compared to a lead brick.

Balance can be done on scales to get started, but needs to be tested to adjust the way a boat carries itself at speed. I have used scales and a saw horse several times, but this is not easy. Even a light weight center steer boat likes a few pounds in front to the driver offet to the left side.

How much and where - is based on what you want. 5 pounds at the bow eye works better than 15 pounds at the front seat.

Get a couple of bags of shot and play around wth them. Just make SURE they are wrapped in plastic and taped up. If not, the lead will oxidize when it gets wet and drain grey stuff all over the boat. A standard bag weighs 25 pounds. If you need less, pour some into a zip lock bag.

You might be amazed how much 15-25 pounds (in the right and wrong places) will change the way your STV (or any boat) drives.

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Does anyone know how much weight they used to put in the bow eye location at the STV racing factory. If I recall it was a rectangular box about the size of a brick? Was it filled with lead shot?

THANKS Guys

I woul run abot 15#'s in the nose and offset to port (side steer)

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OK, so I weighed my boat yesterday. Ready to go to the river, no driver but 20 gals of fuel, 1635#. Hull weighs 27# more on the port side (probably my gear) exactly as I run it.

Now, I'm 170ish, so that puts the Stb side ~140# heavier when I'm one-up. I'm guessing this is why the thing always wants to try to hop on the stb sponson, and why it seems more neutral with a passenger - because it is.

I certainly don't want to add 140# to the port side, what other options do I have?

As I said, I've already moved the battery to the center, in front of the tank:

user posted image

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OK, so I weighed my boat yesterday.  Ready to go to the river, no driver but 20 gals of fuel, 1635#.  Hull weighs 27# more on the port side (probably my gear) exactly as I run it.

Now, I'm 170ish, so that puts the Stb side ~140# heavier when I'm one-up.  I'm guessing this is why the thing always wants to try to hop on the stb sponson, and why it seems more neutral with a passenger - because it is.

I certainly don't want to add 140# to the port side, what other options do I have?

As I said, I've already moved the battery to the center, in front of the tank:

user posted image

Keith, Where was the battery before? Putting the battery in front of the tank is usually what you do with a center steer lighter boat. With your weight boat, I'd put it on the passenger side as far back as possible and toward the edge of the tunnel. Some put it in the sponson but I never have had to move one that far. Try to move what weight you have in the boat first.........then counter it with lead weight. The only time I try to move weight forward is when the nose is flighty. I know you didn't want to hear this after you just moved the battery but it's what I'd do. Haven't really looked over your setup in past post but unless its nose light I'd leave the weight in the tail. Dixon

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Right now my pcs is set up with the bat on the drivers side and the trim pump on the pass side near the back of the tank .when i was in the boat with the lats owner it seemed to me that the back was running low and didnt seem to release from the water ,maybe Anthony can coment on this as he has drove it as well .after driving dreamers rr it feels normal you can feel the back come up and the front drop and the boat lightens up.My thinking is the motor was to low on the pcs before or maybe some weight could be move forward abit.i will be rigging the boat next week but the motor i have is a 200 2.4 and the trim is in the mid and the jackplate wont go on till later in the summer (steering cables to short) so would it be a better idea to put the bat on the pass side and use some lead shot in the left sponson near the pass seat?

My other boat is a sleekcraft tunnel and i used lead shot in the pass sponson and it hepled alot .my last allison you could change the balance just by moving yourself forward in your seat.

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Brian, that boat was originally set up with the monting holes too low for what ever reason. Still pulled 105+....with a jackplate or higher mounting I'm sure it would let go. Don't forget the original owner was a real old guy (like 40) LOL, so maybe Ted set it up ultra conservative......or someone F'd up the mounting height.

The only time it ever ran lopsided was when your lard arse was in the passenger seat ohmy.giflaugh.gif Welcome aboard.

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Dixon, no flightyness. The battery used to be to the stb side of the tank. In the picture, see the round black thing on the left side of the pic (spare prop holder) - that's where it used to be.

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Dixon, no flightyness.  The battery used to be to the stb side of the tank.  In the picture, see the round black thing on the left side of the pic (spare prop holder) - that's where it used to be.

Keith, I personally would put it over by the trim pump as far back as possible and still be easily to get to. I'd move what weight I had in the boat before adding any outside weight. Not sure in your boat but moving a battery of that weight in a lite boat would make a drastic difference. The only time I run a battery where you had it is if I'm running left hand props. The farther from center you move the battery the more affect it will have. Some put it in the sponson but I never felt comfortable with that. I probably would put it fairly close to it though(maybe 5-7" away from fuel tank. I'd try it in front of the trim pump for ease of access. What kind of prop are you running and how much torque steer? What type torque tab?

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